Making yogurt at home saves money, reduces plastic, and keeps a staple probiotic food in the house. Nourishing Traditions recounts research that the lactobacillus acidophilus bacteria in yogurt strengthens resistance to allergies. I make yogurt about once a week to have in breakfast smoothies or use it to make Greek yogurt and whey.
Basic supplies for making yogurt: mason jars, milk, starter yogurt culture.
Heat the milk till bubbles begin to form. If using a thermometer, heat milk to 180ºF. Use a double boiler or stir frequently to prevent scalding. The heating results in a thicker yogurt by encouraging the proteins to coagulate.
While the milk heats, turn the oven to its lowest warm setting, which is usually around 170ºF. Once it preheats turn it off. The warm oven will be used to incubate the yogurt overnight.
Cool the milk to 110ºF, or the point where it feels hot but it does not hurt to keep a clean finger dipped in it. If using a double boiler, speed up the cooling process by replacing the water in the outer pot with cold water.
Add starter culture to the milk. No need to stir.
Cover the milk and place in the warm oven for eight. Do not remove or jostle the yogurt during this time—it can impede the culturing process. You can leave it to ferment longer, resulting a more sour yogurt as the lactose turns into lactic acid.
Ladle into jars and store in the refrigerator for weeks. Save a cup of yogurt for use as the starter culture in your next batch.